The robots are essentially rolling coolers loaded with cameras and sensors that can scan the environment. Starship Technologies, a European company, began manufacturing them as an option for handling food takeout and grocery delivery. An email alerts the customer when the robot reaches his or her door.

The machines weigh about 35 pounds, travel at a top speed of 4 mph and have a range of 2 to 3 miles. They can operate on their own - they're programmed to stop whenever something is directly in front of them - or with a human at the controls.

The bill would limit the robots' operations to sidewalks and crosswalks, set an 80-pound weight limit and a 10-mph speed limit and require operators to control or monitor the devices. It would also prohibit the robots from traveling in roadways and allow local governments to ban them if they so desire.

The robots have been delivering food in Estonia, Germany, Switzerland and the United Kingdom since last year. Pilot delivery programs began in Redwood City, California, and Washington, D.C., in February. Virginia and Idaho have passed legislation similar to the Wisconsin proposal authorizing the robots to operate on those states' sidewalks.

Starship Technologies spokesman David Catania said the company currently has about 150 machines operating around the world. They've traveled 30,000 miles without injuring anyone, he said.

The Wisconsin bill came about after Assembly Speaker Robin Vos saw a demonstration at a National Conference of State Legislatures meeting last year, Catania said. The speaker's staff inquired with the company about bringing the robots to Wisconsin, he said.

The bill's Republican authors, Sen. Chris Kapenga and Rep. Mike Kuglitsch, told the Senate government operations and technology committee that the machines offer an innovative, cost-effective solution to delivery hurdles in the last few miles. Authorizing the machines would signal Wisconsin is a technology leader in the Midwest, they added.

"We need to allow these vehicles on Wisconsin sidewalks and crosswalks," Kuglitsch said. "I believe it is our job as legislators to allow innovation and emerging technologies to prosper and be welcome in our state."